Product classification of Laser Phototypesetting machines
The disadvantages of the external drum type phototypesetting machine are inconvenient operation and low automation. It usually needs manual upper and lower pieces, and needs to be operated in darkroom under hand. Large format imagesetter recording drum, need pumping system and film fixing device, and recording drum bigger, rotation inertia is larger, the speed will be restricted, record low speed, we must rely on increasing the laser beam quantity to improve the recording speed. As a result, this type of phototypesetting machine is seldom used at present.
There are four main types of structure: external drum type, capstan type, inner drum type and hollow drum type. Different structure of phototypesetting machine in performance parameters and operation are different.External drum imagesettersThe outer drum type setter (External drum imagesetters) works with the traditional electrical extension works in a similar way, recording film is attached to the outer circumference of the drum with the roller rotate together, rotates a circle on the record, at the same time, the laser head traversing a line, and then record the next line. The advantages of this type of phototypesetting machine are that the recording accuracy and the registration accuracy are high, the structure is simple, the work is stable, and the record format can be done very large.
However, the structure is very suitable for the roller type plate machine, because the plate is a single version, not the continuous sheet, plate fixed size, and direct plate can operate in the next room, partially offset its disadvantages, and the optical path of the structure is short, easy to control, the laser light loss is small, can to accelerate the speed of multi laser exposure. In addition, the outer drum structure is simple to handle the dust during plate making, and the upper version is the same as the upper version of the printing machine, so the precision can be achieved very high. With the improvement of design level, the degree of automation will continue to improve, so it is considered to be the best direct plate machine structure.
Imagesetters drum (Internal)Also known as an internal drum phototypesetting machine, is considered the best type of phototypesetting machine structure, almost all high-end Phototypesetting machines are using this structure. The structure has the characteristics of high recording accuracy, large format, high automation, simple operation and fast speed, but the price is more expensive than the former two types of phototypesetting machines.An internal drum type phototypesetting machine works by placing the recording film above the inner circumference of the cylinder, the roller and the film motionless, and scanning by the laser beam so that there is no deviation from the unevenness of the film. The laser beam is located on the center axis of the cylinder. The laser can rotate around the center axis. The line L is recorded every 1 weeks, while the laser moves L in the axial direction. It can be seen that the recording distance of the beam from this structure to any point in the film is the same. Therefore, the spot has no deformation and can effectively avoid the problem of reducing the recording accuracy caused by the instability of the film transmission, which is the reason for its very high repeatability. On the other hand, because the cylinder does not move and the beam is deflected by the rotation of the prism, the prism is very light and the moment of inertia is very small, so that the speed can reach very high and the recording speed is very fast.The internal drum type phototypesetting machine also uses continuous film, so it is easy to operate. But the length of the record is limited to the circumference of the drum (usually within half a circle) and cannot be extended as long as a capstan type Phototypesetting machine.
